Af fine tune vs Sigma USB Doc to fine tune focus?

I just picked up a Sigma 35art 1.4 and was thinking of fine tuning the AF on this lens with my Df.

Not sure if I fully understand the difference between fine tuning the AF via custom adjustments on the Df body, versus using the Sigma Doc to tweak the firmware on the lens.

Any sense of which is more effective, easier etc. Why choose one approach versus other (also factor in that I have more than one Nikon body so perhaps its makes sense to adjust the lens, versus each body?) I assume that regardless, you have to use a device like the lens align or similar to get the adjustment factors..?

Any experience using the doc on a MAC/Mavericks OS appreciated - saw one random neg comment on line.